Components of a Computer

In this lesson, we take a look at the different components of a computer system.

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After this lesson, you will be able to

• Define the primary components that make up a computer

Estimated lesson time: 10 minutes

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As you might expect, the components of a computer reflect the function of the machine—specifically, the three stages of computing, as outlined in Lesson 1. Let's examine the components.

Input

The following table lists some examples of devices that are used to put information into a computer.

	Device	Description
	Keyboard	The primary input device for a computer, allowing users to type information just as they once did on a typewriter.
	Mouse	Used with graphical interface environments to point to and select objects on the system's monitor. Can be purchased in a variety of sizes, shapes, and configurations.
	Scanner	Converts printed or photographic information to digital information that can be used by the computer. Works similar to the scanning process of a photocopy machine.
	Microphone	Works like the microphone on a tape recorder. Allows input of voice or music to be converted to digital information and saved to a file.
	CD-ROM/DVD drive	Compact disc–read only memory: stores large amounts of data on a CD that can be read by a computer.

Processing

The central processing unit (CPU) is the heart and brain of the computer. This one component, or "chip," is responsible for all primary number crunching and data management. It is truly the centerpiece of any computer. It is so important that whole generations of computer technology are based and measured on each "new and improved" version of the CPU.

When we refer to the CPU, we are usually speaking of the processor. However, the CPU requires several other components that support it with the management of data to operate. These components, when working in harmony, make up the primary elements of the PC we know today. The following table lists these fundamental support components.

	Component	Description
	Motherboard	The large circuit board found inside the computer. Without it, a computer is just a metal box. The motherboard contains all the remaining items in this table; for all practical purposes, it is the computer.
	Chip set	A group of computer chips or integrated circuits (ICs) that, when working together, manage and control the com- puter system. This set includes the CPU and other chips that control the flow of data throughout the system.
	Data bus	A group of parallel conductors (circuit traces) found on the motherboard and used by the CPU to send and receive data from all the devices in the computer.
	Address bus	A group of parallel conductors (circuit traces) found on the motherboard and used by the CPU to "address" memory locations. Determines which information is sent to, or received from, the data bus.
	Expansion slots	Specialized sockets that allow additional devices called expansion cards or, less commonly, circuit boards, to be attached to the motherboard. Used to expand or customize a computer, they are extensions of the computer's bus system.
	Clock	Establishes the maximum speed at which the processor can execute commands. Not to be confused with the clock that keeps the date and time.
	Battery	Protects unique information about the setup of the computer against loss when electrical power fails or is turned off. Also maintains the external date and time (not to be confused with the CPU's clock).
	Memory	Stores temporary information (in the form of data bits) that the CPU and software need to keep running.

Output

The following table lists some common devices, known as peripherals, used exclusively for output.

	Device	Description
	Printer	Generates a "hard copy" of information. Includes dot matrix, ink jet, and laser varieties.
	Monitor	The primary output device. Visually displays text and graphics.
	Plotter	Similar to a printer, but uses pens to draw an image. Most often used with graphics or drawing programs for very large drawings.
	Speakers	Reproduce sound. Optional high-quality speakers can be added to provide improved output from games and multimedia software.

Input and Output

Some devices handle both input and output functions. These devices are called input/output (I/O) devices, a term you will encounter quite often.

	Device	Description
	Floppy disk drive	Mechanism for reading and writing to low-capacity, removable, magnetic disks. Used to store and easily transport information.
	Hard disk drive	High-capacity internal (and sometimes external) magnetic disks for storing data and program files. Also called fixed disks.
	Modem	Converts computer data to information that can be transmitted over telephone wires and cable lines. Allows communication between computers over long and short distances.
	Network card	An expansion card that allows several computers to connect to each other and share information and programs. Also called network interface card (NIC).
	CD recorder	Also called CD-R. You can copy data to a CD with this device, but you can only write to a section of the disc once. Variations on this type of device include compact disc–rewritable (CD-RW) drives. These drives allow you to read, write, and overwrite a special CD-ROM-type disc.
	Tape drive	Large-capacity, magnetic, data storage devices. Ideal for backup and retrieval of large amounts of data. Works like a tape recorder and saves information in a linear format.

Other external storage devices include Iomega Zip drives, which allow users to store 100 MB or 250 MB of data on a single Zip disk.

Lesson Summary

The following points summarize the main elements of this lesson:

• All computer hardware can be classified by primary function (input, processing, or output).
• Some hardware devices combine multiple functions (input and output).